Abstract
BACKGROUND: Subacute viral infection is known to change the phenotype of infected cells, thereby causing immune-mediated tissue damage. The aim of this study was to investigate the expression of different cell surface molecules on human retinal pigment epithelial cells (RPEC) following viral infection, with special emphasis on those having immune-regulatory functions. METHODS: Cultured RPEC were infected with cytomegalovirus (CMV), coxsackie-virus B3 (CVB) or herpes simplex virus type I (HSV). Double-staining fluorescence technique was used for visualization of virus infection and cell surface markers in the same cells by laser microscopy. RESULTS: CMV downregulated MHC class I antigens on RPEC, whereas CVB and HSV did not alter MHC class I antigen expression. No induction of class II antigens was observed in RPEC infected with CVB, HSV or CMV. The intercellular adhesion molecule ICAM-1 (CD54) was strongly expressed in uninfected RPEC, and a slight increase was observed after virus infection. Vascular cell adhesion molecule 1 (VCAM-1) was expressed in low amounts in both uninfected and infected RPEC. No expression of intercellular adhesion molecule 2 (ICAM-2), E-selectin ELAM-1 or lymphocyte-function-associated antigen 1 (LFA-1) was observed on RPEC before or after virus infection. CONCLUSION: Downmodulation of immune-regulating cell surface antigens has been suggested to provide a means of long-term survival of viruses in the infected cell, favoring establishment of persistent infection. Our observation in cultured human RPEC indicates that this mechanism might indeed contribute to the development of disease affecting retinal tissue.